Is my battery degrading?

[rjpjnk]

The constant is hardcoded in the firmware. The firmware is determined by your car's individual hardware configuration.

(Which gives you an idea of the software development hell tesla is in as the number of unique hardware configs proliferates over time)

As a practical matter, yes, all 2021 MY LR's *running the current firmware* will have the same constant. Your specific VIN was probably not a unicorn whose battery pack or drive units or whatever differed from the cars before and after it on the assembly line.

Perfect. So nice to get a scientifically sound explanation like this. Thank you!

 

[rjpjnk]

fwiw, my battery appears to have degraded appropriately 9% in 10K miles since new. Even though it is a Model Y I feel it is relevant perhaps to the discussion as a data point.

I arrived at this number using my historic TeslaFi charging logs. When new I was seeing 80 kWh capacity and now it is roughly 73. (Actual spec capacity installed is 82.1)

 

[jjrandorin]

fwiw, my battery appears to have degraded appropriately 9% in 10K miles since new. Even though it is a Model Y I feel it is relevant perhaps to the discussion as a data point.

I arrived at this number using my historic TeslaFi charging logs. When new I was seeing 80 kWh capacity and now it is roughly 73. (Actual spec capacity installed is 82.1)

The model Y would be relevant to the model 3. Not so much to the model X (which is the subforum we are in currently).

 

[Harvey Danger]

Yes, the model 3 will definitely have more in common with the model Y, not only because the buffer is determined differently but especially when it comes to how degradation is inferred from the capacity numbers reported when the car is young. (Specifically, the reported capacity for both 3's and Y's is simply pegged to a certain initial number for that car regardless of its actual current capacity for weeks or months until the actual capacity finally drops below that threshold, after which you will finally start to see the *real* capacity from that point forward as it continues to drop. X's (and S's ) don't do that so you won't find much help here trying to figure out what's going on with your car)

 

[rjpjnk]

(Specifically, the reported capacity for both 3's and Y's is simply pegged to a certain initial number for that car regardless of its actual current capacity for weeks or months until the actual capacity finally drops below that threshold, after which you will finally start to see the *real* capacity from that point forward as it continues to drop. X's (and S's ) don't do that so you won't find much help here trying to figure out what's going on with your car)

Thanks for this info. I have been following the M3/MY forums for months yet have never heard of this initial capacity reporting phase, and it certainly matches my data. Can you provide a link to any info/discussion of this? It seems to me there is a higher level of quality information here on the X forums. Maybe smarter people buy X's?

In just a couple days here I learned that the "miles remaining" estimate is really just the kWh remaining estimate times a simple model-based constant, and now I learned that the MY capacity reporting has an "initial reporting phase" that is not based on real capacity estimates. Good stuff. Thank you all.

 

[Harvey Danger]

Can you provide a link to any info/discussion of this?

Look at the sticky threads at the top of this subforum:

Model 3: Battery & Charging

range, battery & charger options, charge time, HPWC

teslamotorsclub.com

In particular I learned a lot from this thread

2020, 2019, 2018 Model 3 Battery Capacities & Charging Constants

I should have done this a while ago, but I've finally compiled all the data that Tesla provides to the EPA, and put it into a spreadsheet. The detailed 2020 test data is now available, so we can see why things are rated the way they are. Through formulas, I've also tried to capture what...

teslamotorsclub.com

In general, forum member AlanSubie4Life has been very consistently helpful in explaining these topics.

Again, most of that stuff will apply to the Model Y. The Model Y forum has its own battery section here, but the moderators there have not created the same kinds of sticky threads that serve as such great references in the model 3 battery subforum.

 

[Ctein]

Dear Folks,

After running the tests several times, I think it's safe for me to say that I've experienced a 6-7% degradation in 2+ years and 20K miles. That doesn't seem excessive. JJ's battery capacity test reports that my battery holds between 91 and 92 KWhr. As Harvey pointed out, Tesla sells the cars specced by range now, not battery capacity. Given the improvements in efficiency over the years, it wouldn't surprise me to learn that my capacity was 2-3 KWhr less than the "official" 100 value previously assigned to my model. So, consistent with the drop in range I've measured.

Thanks to all for their very helpful suggestions!

pax / Ctein

 

[sorka]

You can ask Tesla but I doubt it will take in your issue until it's more than 20% loss in 8 year new car warranty or 125,000 miles whichever first.

Why 125K miles. The S/X are 8 years / 150K miles.

 

[Tam]

Why 125K miles. The S/X are 8 years / 150K miles.

Thanks for the correction.

 

[Tam]

You mean 30%.

Thanks for the correction.

 

[MobileClimate]

mx 2020 here .so the powertrain and battery setpoint to start cooling is at 130-150F that's the temp it wants to see the battery temperature at when supercharging ... When i charge the battery at levl n2 charger 40 F its about 65 percent efficient compared to 100% efficient when the car is at 100F the model x range is effected by temperature big time .its much higher than a model 3 ..my model 3 fans come on at 85 F ..the range mode in the model x is basically telling the car to heat the battery when off and not heat the battery when on .knowing the ambient temperature and battery temp would be the most important factor when looking at the battery capacity for the model x.. maybe the cooling fan setpoint is too high for the model x I dont know. its possible its set so high because people were complaining about the fan noise